Remove set_rollback() from compat (#5591)

* Remove Django 1.6 transaction compat

* Move set_rollback from compat => views

Author: Ryan P Kilby

rest_framework/compat.py

@@ -12,7 +12,7 @@
 from django.conf import settings
 from django.core import validators
 from django.core.exceptions import ImproperlyConfigured
-from django.db import connection, models, transaction
+from django.db import models
 from django.utils import six
 from django.views.generic import View
 
@@ -250,7 +250,7 @@ def md_filter_add_syntax_highlight(md):
 
 # pytz is required from Django 1.11. Remove when dropping Django 1.10 support.
 try:
-    import pytz  # noqa 
+    import pytz  # noqa
     from pytz.exceptions import InvalidTimeError
 except ImportError:
     InvalidTimeError = Exception
@@ -297,23 +297,6 @@ class MaxLengthValidator(CustomValidatorMessage, validators.MaxLengthValidator):
     pass
 
 
-def set_rollback():
-    if hasattr(transaction, 'set_rollback'):
-        if connection.settings_dict.get('ATOMIC_REQUESTS', False):
-            # If running in >=1.6 then mark a rollback as required,
-            # and allow it to be handled by Django.
-            if connection.in_atomic_block:
-                transaction.set_rollback(True)
-    elif transaction.is_managed():
-        # Otherwise handle it explicitly if in managed mode.
-        if transaction.is_dirty():
-            transaction.rollback()
-        transaction.leave_transaction_management()
-    else:
-        # transaction not managed
-        pass
-
-
 def authenticate(request=None, **credentials):
     from django.contrib.auth import authenticate
     if django.VERSION < (1, 11):

rest_framework/views.py

@@ -5,7 +5,7 @@
 
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
-from django.db import models
+from django.db import connection, models, transaction
 from django.http import Http404
 from django.http.response import HttpResponseBase
 from django.utils import six
@@ -16,7 +16,6 @@
 from django.views.generic import View
 
 from rest_framework import exceptions, status
-from rest_framework.compat import set_rollback
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.schemas import AutoSchema
@@ -55,6 +54,12 @@ def get_view_description(view_cls, html=False):
     return description
 
 
+def set_rollback():
+    atomic_requests = connection.settings_dict.get('ATOMIC_REQUESTS', False)
+    if atomic_requests and connection.in_atomic_block:
+        transaction.set_rollback(True)
+
+
 def exception_handler(exc, context):
     """
     Returns the response that should be used for any given exception.